Tobacco



United States Patent TOBACCO Ralph Lawrence Rowland, Winston-Salem, N. C., assignor to R. J. Reynolds Tobacco Company, Winston-Salem, N. C., a corporation of New Jersey No Drawing. Application July 26, 1954, Serial N0. 445,895

Claims. (Cl. 131-17) This invention relates to tobacco and has for an object the provision of a smoking tobacco product having improved aroma and flavor characteristics which become apparent during smoking.

Smoking tobacco as now prepared for use in cigarettes comprises essentially a blended mixture of various types of tobaccos which are desired to produce a characteristic flavor and aroma when the tobacco is smoked. Present day cigarette tobaccos normally comprise blends of (1) heat-cured tobaccos, which are sometimes known as fluecured, bright leaf or Virginia tobaccos, (2) air-cured tobaccos, which are sometimes known as burley or Kentucky and Maryland tobaccos, and (3) sun-cured tobaccos, which are known as Turkish or Oriental tobaccos. The relative proportions of these various types blended to produce a desired cigarette tobacco mixture depend in a large measure upon the characteristic flavor or aroma that is desired to be achieved when the tobacco is smoked. Also it is common practice to add various substances, such as flavoring materials and humectants, in order to provide other desired properties.

A further object of this invention is to provide a smoking tobacco which when smoked will have improved or enhanced flavor and odor characteristics which will be pleasing to the smoker.

A further object of this invention is the provision of a smoking tobacco having added thereto a compound or compounds which, when the tobacco is smoked, will libcrate one or more organic acids imparting a selected and desired flavor and aroma to the smoke.

A still further object of this invention is the provision of a tobacco product having added thereto a substantially nonvolatile substance which in itself does not substantially change the flavor or aroma of the tobacco but which when burned on the tobacco will release to the smoke certain desired flavoror aroma-producing acids.

A still further object of this invention is the provision of additives for tobacco which may be easily and simply prepared and which may be incorporated into the tobacco at any stage during the processing thereof.

Further and additional objects will appear from the following description and the appended claims.

III the copending application of Samuel OBrien Jones, Serial No. 445,891, filed July 26, 1954, it is disclosed that certain esters of flavor-producing acids when added to tobacco will, when smoked or burned with the tobacco, release the acid or acids which latter impart a desired characteristic odor and/or flavor to the smoke, thereby contributing to the enjoyment of the smoker.

In accordance with the broad aspects of-this'invention, a smoking tobacco composition is provided which contains as an additive a small amount of an ester of an enol type compound. It has been found that esters of this type, when smoked or burned with the tobacco, will release a high percentage of the esterifying acids which, to provide the desired flavor and aroma, are those having from 3 to 8 carbon atoms. These acids, when present in the smoke in suitable concentrations, impart characteris- 3='( JOH These enols are organic hydroxy compounds and the group may be positioned in the ring structure of a homocyclic or heterocyclic compound or may form a portion of the aliphatic group in a substituted or unsubstituted aliphatic compound. Typical homocyclic enols that may be esterified to form the additives for use in accordance with this invention are:

H2 0 9) H20 OOH H o H nir z (Eon 2 0 H20 o-ona Hi 2-hydroxy-3-methyl- 2-cycl0pentene-1-one Such homocyclic enols also include other derivatives of cyclopentene, cyclohexene and various aromatic compounds having a single or condensed ring structure, e. g. hydroxyquinones and polyhydro'xyquinones. Typical heterocyclic enols that may be esterified to form the additives for use in accordance with this invention are:

l-eyelohexenol Such heterocyclic enols also include the derivatives of other compounds having the furan, thiophene, pyr-role, pyridine, pyrone, pyrylium base, indole, quinoline or isoquinoline nucleus. Typical-compounds in which the enol group forms a portion of the aliphatic group inan aryl substituted or unsubstituted aliphatic compound and which may be esterified to'form the additives for use in accordance with this invention are:

\CH ta H 2-carbethoxy-l-phenylvinyl alcohol 0 HIE ozHs'o' -C=COH Ha 2-carbethoxy-Lmethylvinyl alcohol H (I) OOH C25.. C2. H 0d i H on on 2-carbethoxy-1,4-pentadiene l-ol and it is the hydroxyl group associated with this grouping that is esterified with the flavoring acid to produce the esters for incorporation into tobacco in accordance with this invention.

The flavor-producing acids which are released by the esters in accordance with this invention are preferably those flavoring acids which will volatilize and will be carried by the smoke, such acids usually being the organic carboxylic acids having 3, 4, 5, 6, 7 or 8 carbon atoms, herein collectively referred to as those having from 3 to 8 carbon atoms. Representative acids are the saturated aliphatic fatty acids, such as propionic, n-butyric, isobutyric, n-valeric, isovaleric, Z-methylbutyric, n-caproic, 4- methylvaleric, 3-methylvaleric, 2,2-dimethylbutyric, 2- methylisovaleric, straight or branched chain heptoic, or straight or branched chain caprylic acids; the unsaturated aliphatic fatty acids, such as acrylic, crotonic, vinylacetic, 4-methyl-4-hexenoic and S-methylsorbic acids; the cycloalkane or cycloalkene aliphatic acids, such as cyclopentanecarboxylic, cyclohexanecarboxylic, cyclopentaneacetic or cyclohexaneacetic acids or the corresponding unsaturated cycloalkenes; the aromatic carboxylic acids, such as benzoic or toluic acids; and phenylacetic acid. Also the volatile derivatives of such acids, such as hydroxy acids or keto acids may be the acid compound released to impart the desired odor or flavor to the smoke. It is preferred that the flavoring acid be an aliphatic or alicyclic saturated monocarboxylic acid of the fatty acid series having 4, 5 or 6 carbon atoms, herein collectively referred to as those having from 4 to 6 carbon atoms.

It will be apparent that the ester additive may be selected or prepared in such a manner that any one of the foregoing acids will be released during smoking. Also a mixture of additives may be selected and added to the tobacco so that a plurality of desired flavoring acids may i be simultaneously liberated if desired, thus effecting a blend of the various types of aromas which has the characteristics of the several flavoring acids. It will also be apparent that the compound may be one which contains more than one esterified hydroXyl group and in such event the several hydroxyl groups may be esterified with one or more different flavoring acids or less than all of the hydroxyl groups may be esterified to produce the additive used in accordance with this invention. However, in accordance with this invention it is important that the esterified hydroxyl group be attached to a carbon atom which is next to a double bond. The specific flavor-producing acid or acids that are combined with the hydroxy compound to form the ester will depend upon the flavor and aroma desired in the tobacco smoke. As indicated above, the particular flavoring acid selected for the preparation of the ester is of consequence only in so far as the particular flavor contributed by that particular acid is important. Any of the flavor-producing acids may be utilized and, as previously indicated, they generally comprise the saturated or unsaturated organic carboxylic acids containing from 3 to 8 carbon atoms, preferably the saturated aliphatic monocarboxylic acids having from 4 to 6 carbon atoms.

The additives contemplated by this invention may be I incorporated into the tobacco in any desired manner. For example, solutions of the additive in a suitable solvent, such as alcohol, ethyl ether, acetone or the like, may be applied to the tobacco as by spraying or otherwise,

whereafter the solvent is driven off as a vapor leaving the additive thoroughly incorporated with the tobacco. The additive may also be uniformly dispersed in water and applied in a like manner if desired. The incorporation of the additive may take place at any time prior to the final packaging of the tobacco product. In the case of cigarette tobacco, it may be incorporated before or after blending of the various tobaccos if, in fact, blended tobacco is employed, and the additives may be applied to one or all of the blend constituents. Under certain circumstances the additive may be incorporated into the tobacco before aging and curing, however, this would not ordinarily be done if the additive has a tendency to decompose during the aging and curing process. In the case of cigarettes the additive in some instances might be applied to the paper instead of to the tobacco.

The amount of additive in the final product contemplated by this invention is quite small but will vary widely with the particular additive employed and the amount of acid released upon burning or the flavor or aroma desired in the smoke. Thus an additive that releases only a comparatively small fraction of its total available flavoring acid on burning will be required in higher concentrations than those additives which are more eflicient with respect to the amount of flavoring acid released. Also it is well known that some of the aliphatic fatty acids having from 4 to 6 carbon atoms have a disagreeable odor per so when vapors of these acids are smelled in certain concentrations. However, in very low concentrations they provide in the tobacco smoke a desirable flavor and aroma, and the amount of additive in the tobacco should be such as not to exceed the amount which, when the tobacco is smoked, will release desirable quantities of the acid. This amount in many cases will be determined by actual experimentation. Generally speaking, however, desirable flavor and aroma are produced if the additives are incorporated into the final tobacco product in amounts between about 0.01 and 1.0 percent by weight (dry basis).

As pointed out in the copending Jones application hereinbefore referred to, a number of methods have been employed for incorporating acid-releasing compounds into cigarette tobacco and evaluating them for acid release. Certain of such methods are suggestive of procedures that may be used in actual commercial practice and include the following:

METHOD 1 One gram of shredded flue-cured tobacco was spread out on a watch glass of 10 cm. diameter. One milliliter of a solution of the additive in a suitable solvent such as ethyl ether was added uniformly to the tobacco from a pipette. The amounts of the additives vary but in general 10 milligrams of additive were applied to the one gram sample. After the ether had evaporated the tobacco was rolled into a cigarette which was stored at 75 F. and about 60% relative humidity.

METHOD 2 A small quantity of liquid additive in the amount of 1 to to 5 milligrams was streaked longitudinally along the paper of a cigarette by means of a stirring rod.

METHOD 3 The additive was dissolved in a volatile solvent, such as acetone, alcohol or ether, using 2 to 40 milligrams of additive per milliliter of solvent. One-fourth milliliter of the resulting solution was then distributed through a oneinch portion (which was to be burned) of a cigarette by means of a milliliter hypodermic syringe. The volatile solvent was then blown out of the cigarette with a stream of compressed air, leaving the additive dispersed in the cigarette.

METHOD 4 The additive was dissolved in ethyl alcohol or other suitable solvent and sprayed onto shredded flue-cured tobacco spread out on a table. Two hundred milliliters of solution containing 1 to 20 grams of additive were used for each 3 kilograms of tobacco. The tobacco was exposed to the air until substantially all of the Solvent had evaporated and then was manufactured into cigarettes in the usual manner having an average weight of one gram each. These were stored for a period of 1 to 12 months at 75 F. and 60% relative humidity in order to ascertain the stability of the additive when stored on tobacco.

METHOD The additive was dissolved in alcohol or other suitable solvent and sprayed onto one of the types of leaf tobacco that are used in a blended cigarette. This leaf tobacco was allowed to dry and was cut on a shredding machine. The shredded tobacco was blended with other types of shredded tobaccos that had not been treated with additive and the blend was made into cigarettes.

The compound or additive under test when applied to a low flavor tobacco or a cigarette made therefrom as indicated in one of the foregoing methods was evaluated by organoleptic testing. This was carried out by smoking the cigarette and examining the smoke by sensory methods. In each of these tests special efforts were made to determine whether any acid odor was present in the smoke. This included a careful sensory study of both the main stream and the side stream. If the acid odor was detected in either the side stream or the main stream, it was concluded that the additive released the acid during the smoking or burning of the treated tobacco or cigarette.

In the foregoing, reference has been made to a general class of esters which are useful as additives for tobacco in accordance with this invention. These comprise the esters of enol type compounds as previously described. Certain of the specific compounds in this class are new and certain of them are not available commercially. Accordingly, several examples will be presented in the following disclosing methods of preparing representative compounds that are useful as additives in accordance with this invention. In each case the compounds which were prepared by the specific procedures given in the examples to follow were tested by one of the methods previously mentioned and each was found to release a high percentage of flavoring acid when smoked with tobacco. It will be understood that in the following, examples are given of preparing esters which will, upon burning or smoking of a tobacco treated therewith, liberate only a single flavor-producing acid. However, it will be apparent to one skilled in the art how other esters releasing other particular flavoring acids may be prepared. For example, in the following where there are given examples of processes of preparing esters of certain specific flavoring acids, it will be understood that essentially the same or similar means known to chemists could be employed for preparing the esters of other flavoring acids of the character hereinabove specified and that all such esters are contemplated as additives within the scope of this invention.

Il Ialtol 3-methylvaleraze To a cooled mixture of 100 milliliters of chloroform, 15.8 grams of pyridine and 29.5 grams of 3-methylvaleryl chloride were added 25.2 grams of 2-methyl-3-hydroxypyrone. The reaction mixture was allowed to warm to room temperature and was then heated under reflux. The mixture was diluted with 200 milliliters of ether and was washed successively with 100 milliliters of water, 100 milliters of 2N sulfuric acid, 100 milliliters of water, 100 milliliters of 5 percent sodium bicarbonate solution and 100 milliliters of water. After the ethereal solution was dried over calcium chloride, the low-boiling solvents were removed under reduced pressure. The residue was distilled under reduced pressure. The material boiling at 107111 C. at 0.08 mm. Hg weighed 30.4 grams (70 percent).

5-ket0-2-methyl-1-cycl0pentenyl isovalerate To a mixture of 15 grams of 2-hydroxy-3-methyl-2- cyclopentene-l-one (Bush Aromatic), 100 milliliters of chloroform and 10 milliliters of pyridine cooled in a Dry Ice bath, 15 grams of isovaleryl chloride were added rapidly. The mixture was allowed to stand in the Dry Ice bath for 20 hours after which it was diluted with 300 milliters of ether. The ethereal solution was washed with 70 milliliters of 2N sulfuric acid and then with milliliters of water. After the mixture was dried over calcium chloride, the low-boiling solvents were removed under reduced pressure. The product, which was collected by distillation at 9497 C. at 0.4 mm. Hg, weighed 13.3 grams (75 percent).

Ascorbic acid tetracyclopentanecarboxylate To a mixture of 8.8 grams of l-ascorbic acid, 100 milliters of chloroform and 16 grams of pyridine cooled in a Dry Ice bath were added rapidly 27 grams of cyclopentanecarboxyl chloride. After 15 minutes the reaction mixture was allowed to warm to room temperature. The mixture was then heated under reflux for one hour. After dilution with 200 milliliters of ether, the mixture was washed successively with 100 milliliters of water, two 50- milliliters portions of 2N sulfuric acid and 100 milliliters of water. The ethereal solution was dried over anhydrous sodium sulfate and the ether was removed by distillation. The residual oil comprising the desired ester weighed 20 grams.

lsoascorbic acid tetrabenzoate To a mixture of 8.8 grams of isoascorbic acid and 70 milliliters of chloroform cooled in a Dry Ice bath were added dropwise with stirring 36.5 grams of benzoyl chloride. To this mixture were added 22 grams of pyridine. The reaction mixture was allowed to warm to room temperature. After three days the mixture was diluted with 200 milliliters of ether and was washed successively with 100 milliliters of water, two 100-milliliter portions of 5% sodium bicarbonate solution and 100 milliliters of water. The ethereal solution was dried over calcium chloride after which the ether was removed under reduced pressure. The residue was dissolved in benzene and the benzene was then removed by distillation under reduced pressure. The residue was extracted with two 100-milliliter portions of hexane and with three 70-milliliter portions of warm isopropyl ether. The insoluble residue was crystallized three times from toluene to give 2.6 grams of solid melting at 147-148 C.

It will be understood that the foregoing specific examples are only representative of the large number of esters of the various enols that may be used to release acid on smoking of a tobacco treated therewith. It will also be understood that these compounds may be prepared by other methods that are well known to the art generally. The specific examples given are believed to be adequate to show the manner in which a large number of esters of the various hydroxy compounds and the several flavoring acids may be readily prepared.

A specific example of a method for incorporating an additive into tobacco to produce a composition in accordance with this invention is as follows: Twenty milligrams of 5keto-2-methyl-l-cyclopentenyl isovalerate were dissolved in 10 milliliters of acetone and injected into test cigarettes as follows. One-quarter milliliter of the solution Was distributed through the end portion of a fluecured cigarette by means of a Ai-milliliter hypodermic syringe, and the volatile solvent was blown out of the cigarette by means of a stream of compressed air, leaving the fiavorant dispersed in the tobacco. Several cigarettes were prepared in this manner and examined by a panel of smokers, care being taken to light the treated end of each cigarette. Isovaleric acid was detected in the mainstream and sidestream smoke from the cigarettes.

As pointed out in the above mentioned copending Jones application, studies have been made in order to determine the extent to which various compounds will actually release acid when smoked with tobacco. Upon an organoleptic test basis the esters of the enols have been determined to release relatively large amounts of acid when the tobacco treated therewith is burned or smoked. This high degree of acid release is believed to be due, at least in part, to the fact that the esterified hydroxyl group is attached to the carbon atom adjacent the double bond thereby facilitating cleavage in that portion of the molecule. As will be apparent from the foregoing description, the esterified enol may contain additional ester groups which may or may not be adjacent an enolic carbon atom but which also contribute to the total amount of acid released upon burning or smoking of a tobacco treated therewith.

It will be understood that compositions have been prepared in accordance with this invention which have improved or enhanced aroma and flavor to give increased pleasure during smoking. Infinite variations with respect to the kinds and amounts of flavor-producing acids are possible and may be readily controlled. Such flavorproducing esters may be particularly useful with tobaccos which are ordinarily low in the type of flavor imparted by the flavoring acids. While the invention has been specifically described with reference to cigarettes, it will be apparent that it has application in the manufacture of other smoking tobaccos such as used for hand-rolled cigarettes, pipes and cigars.

While several particular embodiments of this invention are shown above, it will be understood, of course, that the invention is not to be limited thereto, since many modifications may be made, and it is contemplated, therefore, by the appended claims, to cover any such modifications as fall within the true spirit and scope of this invention.

I claim:

1. An article of manufacture comprising tobacco and an ester of a volatile organic acid and an enol type compound.

2. A smoking tobacco having added thereto a small amount of an ester of an enol and a volatile organic flavoring acid having at least three carbon atoms.

3. A smoking tobacco having added thereto a small amount of an ester of an organic acid having from 3 to 8 carbon atoms and an unsaturated organic enol type hydroxy compound in which the esterified hydroxyl group is positioned on a carbon atom adjacent the double bond in said compound.

4. The tobacco recited in claim 3 in which said carbon atom is a member of a homocyclic ring.

5. The tobacco recited in claim 3 in which said carbon atom is a member of a heterocyclic ring.

6. The tobacco recited in claim 3 in which said carbon atom is a member of an aliphatic group in said compound.

7. A smoking tobacco having added thereto a small amount of a substantially nonvolatile ester of a volatile monocarboxylic acid having from 3 to 8 carbon atoms and an unsaturated organic enol type hydroxy compound in which the esterified hydroxyl group is positioned on a carbon atom adjacent the double bond in said compound.

8. A smoking tobacco having added thereto between about 0.01 and 1.0 percent by weight of a substantially non-volatile ester of a volatile monocarboxylic aliphatic acid having from 3 to 8 carbon atoms and an enol.

9. The tobacco recited in claim 8 wherein said acid has from 4 to 6 carbon atoms.

10. An article of manufacture comprising tobacco and an ester of a volatile organic acid and an enol selected from the group consisting of a maltol, 2-hydroxy-3- methyl-Z-cyclopentene-l-one, ascorbic acid and isoascorbic acid.

11. A smoking tobacco having added thereto between about 0.01 and 1.0 percent by weight of an ester of a volatile monocarboxylic flavoring acid having from 3 to 8 carbon atoms and an enol selected from the group consisting of a maltol. 2-hydroxy-3-methyl-2-cyclopentene-1- one, ascorbic acid and isoascorbic acid.

12. The tobacco recited in claim 11 wherein said enol is maltol.

13. The tobacco recited in claim 11 wherein said enol is 2-hydr0xy-3-methyl-2-cyclopentene-l-one.

14. The tobacco recited in claim 11 wherein said enol is ascorbic acid.

15. The tobacco recited in claim 11 wherein said enol is isoascorbic acid.

OTHER REFERENCES M. B. Jacobs: Synthetic Food Adjuncts, page 119. Published 1947 by D. Van Nostrand Co., New York, N. Y. 

1. AN ARTICLE OF MANUFACTURE COMPRISING TOBACCO AND AN ESTER OF A VOLATILE ORGANIC ACID AND AN ENOL TYPE COMPOUND. 